Why is there river sludge in the engine?

Please tell me... Why is there river sludge in the front cylinder?

The rear piston and cylinder look pretty good for not operating within a year or more.

The cylinders and heads are free! Apparently using daily sprays of penetrating oil for a few weeks caused the piston and cylinder to release their unnatural hold on each other. It was a surprise, really. I wanted to lift the engine onto a work bench. Working on an engine setting on the ground is simply not very good on my knees. I am still taking ibuprofin for the pain caused by my afternoon of work a few weeks ago.

Anyway, I gripped the cylinders, thinking the whole engine would lift. I wish I had a camera on my face when the cylinders just slipped up and off the pistons!




Looks like I have my work cut out for me. Hopefully I will not need to split the engine case, but first things first. The pistons, heads and cylinders need to be completely disassembled and checked. Hopefully they can be restored but I have a bad feeling about that front cylinder and piston.